new to prp have a quick question.

[green99_svt]

so I wrote my first tune a few weeks back and finally finished the new setup. i've done the first two revisions on the maf transfer function based on the data logs. is it normal to see the initial tune to be lean by 30%? I used the value files in advantage for cobra 39lb injectors andBA500 in a 3" tube. In that order. I added 20% at idle and 25% on all other counts the first revision and, 5% at idle and 10% on the other second time around. The car runs pretty good now after the revisions but the amount lean seamed excessive, I figured it would be in the 5-10% range like in the vids. should I continue fine tuning it or look for other issues?

also a little about the setup
99 cobra - stock long block with fr500 cams
03 39lb injectors
ba5000 in blow through 3" tube.
vortech s-trim 3.33" pulley, fmic
long tubes
03 tank and pumps.

 

[ctgreddy]

The only thing to really check for would be a vacuum leak. Look at all your rubber hoses, with the car idleing spray everything with brake clean and listen for idle changes. If you don't find anything I wouldn't worry about it. From what I've found is the value files are pretty far off on most maf stuff. All it really does is get you close enough to get the car running enough to log. When I switched to a slot style I had to try 2 different value files and ended up with a car with a steeda cai file, but still added 15-20%. No issues since I've tuned it closer.

 

[green99_svt]

Ok thanks, I've double checked for leaks and I have good vacuum so I guess they are just that far off to start.

 

[Catmonkey]

So what size is the MAF tube you're using?

 

[crfrider16]

What ctgreddy said. It's not abnormal to have to pull or add huge amounts of fuel to get it right. Value files are ball park at best.

 

[green99_svt]

Great sounds like it's normal then.

I'm using a ba5000 in a 3" tube. The tube is approximately 18" long and the sensor is about 2/3 of the way up.

 

[MalcolmV8]

As mentioned above the MAF value files are just ball parks. I don't even use them anymore. I just take the stock curve and add or remove as needed to get the car running then using data logs fine tune it.